1. Field of the Invention
This invention relates to an amorphous magnetic thin film for use in such plane magnetic elements as plane inductors and plane transformers and plane magnetic elements using the amorphous magnetic thin film.
2. Description of the Related Art
In recent years, the miniaturization of various electronic devices has been advancing at a lively space. In the meanwhile, the miniaturization of power source parts of the electronic devices has been proceeding slowly as compared with that of the electronic devices. As a result, the ratios of the volumes occupied by the power source parts to the whole volumes of the electronic devices are incessantly growing. The miniaturization of electronic devices hinges heavily on the realization of LSI with various circuits. Such miniaturization or integration, however, has been advancing slowly on such magnetic parts as inductors and transformers which are essential for the power source parts. This delay forms the main cause for the growth of the volumetric ratios of the power source parts.
For the solution of this problem, plane magnetic elements which severally combine a plane coil with a magnetic thin film have been proposed. Studies are being made in search of a method which is capable of imparting exalted performance to these plane magnetic elements. The magnetic thin film to be used in these plane magnetic elements is required to suffer only low loss and enjoy high saturation magnetization in a high frequency range of 1 MHz or more. It is suspected that the compatibility of low loss and high saturation magnetization at a high frequency will gain all the more in importance as the working frequencies of magnetic elements shift to the range of 10 MHz to 100 MHz in the future. For example, in the high frequency applying magnetic field, since the eddy current loss is conspicuous, alleviation of this loss necessitates lamination of magnetic films or impartation of exalted resistivity to individual magnetic films. High saturation magnetization forms an indispensable requirement for the purpose of increasing inductance density or energy density.
Even in the case of thin-film magnetic heads other than plane magnetic elements, it is only natural that magnetic thin films which concurrently enjoy low loss and high saturation magnetization in a high frequency range should effectively manifest their functions in proportion as the recording density increases, the recording media tend toward higher coercive force and higher energy product, and the operating frequency augments. These requirements are imposed as well on other magnetic elements.
Incidentally in the high frequency range, the permeability is mainly procured in the magnetization reversal of rotation. As a result, the applying magnetic field in the direction of the hard axis of magnetization gains in importance and the high frequency permeability and the high frequency loss in the direction of the hard axis of magnetization constitute themselves important physical properties. The high frequency permeability is associated with various physical properties, sapecially, magnetic anisotropy field. The high frequency permeability varies generally in proportion to the reciprocal of the magnetic anisotropy field. For the purpose of realizing high saturation magnetization, low loss, and high permeability in the high frequency range mentioned above, therefore, uniaxial anisotropy in the film planes and suitable uniaxial magnetic anisotropy energy are necessary for the soft magnetic thin films.
For the sake of satisfying the properties which magnetic thin films are required to possess as described above, such ordinary magnetic thin films as are made of a transition metal offer unduly low resistivity and necessitate a complicated structure such as lamination. This necessity entails complication of the process of production and addition to the cost of production. Such oxide type materials as soft ferrites which have high resistivity are deficient in saturation magnetization and unfit for the sake of miniaturizing devices and exalting the output.
For the purpose of overcoming these drawbacks of the conventional materials, efforts are being devoted now to the research and development of heteroamorphous films (refer, for example, to Laid-open Japanese Pattent Application SHO.63-119,209). The soft magnetic thin film which is disclosed in Laid-open Japanese Pattent Application SHO.63-119,209, however, is substantially isotropic magnetically, though it concurrently acquires high saturation magnetization and high resistivity. It does not fit the purpose of imparting and controlling the permeability which is optimized for the properties owned by a given magnetic element. Particularly, microminiaturized thin film inductance elements necessitate an inplane uniaxial magnetic anisotropy of a specific magnitude.
The plane magnetic elements intended for miniaturization, as described above, demand soft magnetic thin films which concurrently satisfy high saturation magnetization and low loss in the high frequency range. Further, for the purpose of imparting a desired high frequency permeability to plane magnetic elements, acquisition of the high frequency permeability by applying magnetic field in the hard axis of magnetization constitutes itself an important requirement. It becomes necessary, therefore, to impart inplane uniaxial magnetic anisotropy to the magnetic thin films and, at the same time, to heighten the controllability of this anisotropy. In the circumstances, the desirability of developing a soft magnetic thin film which easily acquires desired high frequency permeability by applying magnetic field in the hard axis of magnetization and, at the same time, satisfies high saturation magnetization and high resistivity by the impartation and control of the inplane uniaxial magnetic anisotropy has been finding enthusiastic recognition.